This invention relates to novel naphthalocyanine compounds and a method for preparing the same. More particularly, it relates to nitro-substituted naphthalocyanine compounds, amino-substituted naphthalocyanine compounds, vinyl-containing naphthalocyanine compounds, and methods for preparing them. It also relates to a novel naphthalocyanine polymer obtained by starting with the novel vinyl-containing naphthalocyanine compound and a method for preparing the same.
Phthalocyanines and naphthalocyanines which are derivatives thereof are macrocyclic dyes having a structure similar to porphyrin compounds and they are stable against light, heat and moisture, chemically stable and fast. Especially metal phthalocyanines have been widely used as dyes or pigments because of their high stability and definite color tone. They now draw interest as materials for light absorption, electric conduction, photo-conduction, energy conversion, electrode and catalyst because of the presence of a metal ion in a large .pi.-electron conjugated system. However, they are essentially difficult to dissolve, to work up to high purity, and to handle under ambient conditions.
Attempts were made to produce a polymer having carried thereon a phthalocyanine, especially a metal phthalocyanine for facilitating formation of films or similar items capable of exerting a high function. Such a metal phthalocyanine-containing polymer is produced, for example, by synthesizing a metal phthalocyanine derivative having a reactive group and reacting it with a polymer having introduced therein a group reactive with the reactive group. See D. Wohrle et al., J. Org. Organomet. Polym., 1, 1,115 (1991). This type of synthetic method wherein a metal phthalocyanine derivative is reacted with a polymer, however, suffers from the problem that the reaction product has an inconsistent content of metal phthalocyanine ring.
Also proposed were metal phthalocyanine derivatives which have a vinyl group and are thus polymerizable by themselves as disclosed in Japanese Patent Application Kokai (JP-A) Nos. 178672/1985 and 53990/1987. It was also attempted to produce polymers by starting with them as disclosed in JP-A 50311/1987. The metal phthalocyanine derivatives are obtained by starting with a metal phthalocyanine tetracarboxylic acid and introducing a vinyl group therein. Synthesis of a metal phthalocyanine tetracarboxylic acid entails formation of much by-products probably because of solid-phase reaction. Also most intermediates to the vinyl group-containing metal phthalocyanine derivatives are sparingly soluble and difficult to purify. Then the final products are low in purity. While vinyl groups are introduced in a number proportional to the number of carboxy groups and thus typically four vinyl groups are introduced, often those products having vinyl groups in a number other than the desired number are concomitantly produced, which are difficult to separate and thus cause a lowering of purity. Moreover, the vinyl group-containing metal phthalocyanine derivatives are less soluble.
The resulting polymer is often a three-dimensional polymer since the metal phthalocyanine derivative has four vinyl groups as a general rule. This complies with the purpose of having a vinyl polymer carry a metal phthalocyanine like a crosslinking agent, but not with the purpose of synthesizing a linear polymer.
The problems discussed above also apply to naphthalocyanine compounds.
It is thus desired to develop a polymerizable naphthalocyanine compound having improved solubility and purity and offering a freedom of choice of a ligand metal to the naphthalocyanine. It is also desired to produce a polymer from the naphthalocyanine compound as a starting monomer, the polymer having improved solubility, high purity, easy control of orientation, and a high naphthalocyanine content.